This invention relates to furniture that supports a person by webbing slung on a frame, and more particularly to an improved means for attaching the webbing to the frame.
Slung furniture is not only economical, but also comfortable because the fabric flexes to conform to one's body. A common way of attaching the webbing is by means of a hem and welting that are inserted into a channel in the frame; the hem is locked in because the channel opening is narrower than the welting. This limits design because the hem and welting must be inserted from the end of the channel. In particular, the webbing can not be attached around its entire perimeter. It would be better if one could simply lay hem and welting in a channel, and somehow lock them in.
One approach is to use welting that is not round, so it can be placed in the channel then turned to resist being pulled out. Lovell (1930) and Wisner (1930) disclose essentially the same welt lock system that uses double round or oblong welting in the hem of upholstery. This holds it in a specially shaped channel because the welting comes to bear on a front wall of that channel. Similarly, Hoven (1951) describes an oval or flat spring in a hem that holds the edge of upholstery within an oval channel. With this kind of arrangement, however, the hem may fall out of the channel when there is slack in the upholstery, and such systems are not intended to support the weight of a person.
The present invention uses a better approach, using a locking strip to secure hem and welting in a channel. The locking arrangement is a form of synergy, in which the locking strip and the other elements hold each other securely in position.
Only a few patents involve welting and any sort of locking strip, and these locking strips are quite different from the present invention. Austin (1956) discloses a method in which a hem and welting are laid in a channel, then locked in by a stiff block that is forced into the channel "by pounding or otherwise". The block is held in place by pressure, friction, and a ridge on the block that engages a notch in the side of the channel. There is no provision for removal of the block. Babbs (1974) discloses a U-shaped extrusion that is "welded" by radio frequency waves to the edge of fabric, hooked over one edge of a channel, and held in place by a second extrusion that is forced into the channel. The second extrusion has cavities to provide the necessary compressibility. This method is appropriate only for light duty applications, because the welding is not likely to support the weight of a person. Koepke (1983) discloses a strip that is stapled to one edge of a channel, to provide a tight fit when a hem and welting are subsequently forced into the channel. Since Hoepke's strip is placed first it cannot truly block removal of the hem and welting. None of these systems involves a locking strip that is placed in the channel under the webbing after the hem and welting are inserted, as does the present invention, nor do they provide any means for removal of the webbing for cleaning or replacement.
One object of the present invention is slung furniture that supports the weight of a person by means of a hem and welting that can be laid in a channel, without having to insert them from the end of the channel. Another object is to lock the hem and welting in a channel with a locking strip in an arrangement where these elements hold each other neatly in position. Another object is a means to install and remove the locking strip, so that the webbing can be cleaned, repaired, or replaced. Finally, another object is to make the channel with flexible stock welded to a frame of standard steel tubing.